A dissipation study of pesticides in soil is essential as it is a major sink for bulk of globally used pesticides. Soil properties, temperature and application rate play important role in its degradation. Laboratory studies were carried out in order to assess the degradation dynamics of imazethapyr under subtropical conditions. In all soils, at all studied temperatures dissipation followed single first-order kinetics at lower application rates (0.0375 and 0.187 µg g⁻¹) with half-life varying from 30.15 to 52.16 days. However, at higher application rate (0.8 and 1.5 µg g⁻¹), dissipation followed biphasic first-order kinetics and half-life varied from 6.57 to 7.79 days (p > 0.05) during initial phase and 93.74–152.83 days (p < 0.05) during final phase. Dissipation rate was fastest in alkaline soils (pH = 8.0–8.8) followed by neutral soil (pH = 7.4) and acidic soil (pH = 5.0). Amendment of soil with farmyard manure and increase in temperature enhanced the dissipation of imazethapyr. Application of imazethapyr at low rate has nonsignificant effect on dehydrogenase and alkaline phosphates activity, whereas short and momentary toxic effect was observed at 0.8 and 1.5 µg g⁻¹. These findings indicate that soil physicochemical parameters especially pH, OM content and temperature should be considered in combination along with the application rate of imazethapyr for achieving satisfactory weed control and reducing environmental risk associated with the use of imazethapyr in different crops.

对农药在土壤中的耗散情况的研究至关重要，因为它是大量使用全球农药的主要汇。土壤性质，温度和施用量在其降解中起重要作用。为了评估咪唑乙烟在亚热带条件下的降解动力学，进行了实验室研究。在所有研究的土壤中，在较低的施用量（0.0375和0.187 µg g ^-1）下，耗散遵循单一的一级动力学，半衰期从30.15天到52.16天不等。但是，在较高的施用量（0.8和1.5 µg g ^-1）下，耗散遵循双相一阶动力学， 初始阶段的半衰期从6.57天到7.79天（p > 0.05）变化，在最初阶段是93.74-152.83天（p <0.05）。在碱性土壤（pH = 8.0–8.8）中消散速度最快，其次是中性土壤（pH = 7.4）和酸性土壤（pH = 5.0）。用农家肥对土壤进行改良并提高温度可提高咪唑乙烟的耗散。咪唑乙烟碱的低用量对脱氢酶和碱性磷酸酯酶活性没有显着影响，而在0.8和1.5 µg g ^-1时观察到短暂和短暂的毒性作用。这些发现表明，应综合考虑土壤理化参数（尤其是pH，OM含量和温度）以及咪唑乙烟的施用量，以实现满意的杂草控制并减少与在不同作物中使用咪唑乙烟相关的环境风险。